Extending battery life tenfold

Researchers at Stanford University have revised technology to increase lithium-ion battery charge capacity ten times. It could mean running a notebook for 40-hours between charges.

By
Chris Mellor
| Dec 20, 2007

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Researchers at Stanford University have revised technology to increase lithium-ion battery charge capacity ten times. It could mean running a notebook for 40-hours between charges.

Lithium-ion batteries, commonly used for notebook computers, mobile phones and other mobile intelligent devices, store their charge in a part called the anode. Here lithium ions are taken up by a holding material, typically carbon, when the battery is charged and released as it discharges and powers the device.

The use of silicon as a holding material, theoretically attractive as it holds more lithium than carbon, has been hindered because it swells up fourfold as it absorbs the lithium when charging, and shrinks as power is drawn out. This repeated change in the material causes it to fracture, rendering such a battery progressively less and less powerful.

Yet by building the substrate out of silicon nanowires, the research team led by Yi Cui, assistant professor of materials science and engineering at Stanford University, has countered this problem. The silicon nanowires also enlarge four times their original size as they take up the Lithium but remain stable as they release it and then take it up again. The resulting battery is able to hold ten times as much lithium, meaning ten times more charge.

The silicon nanowires are said to have a diameter one thousandth of the thickness of a sheet of paper.

More technical details are described in a paper: "High-performance lithium battery anodes using silicon nanowires," published online on December 16th in Nature Nanotechnology, written by Cui and his team of six researchers. The paper is available for a one-off fee or via a Nature Nanotechnology subscription.

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Cui said: "It's not a small improvement. It's a revolutionary development ... Given the mature infrastructure behind silicon, this new technology can be pushed to real life quickly," understood to mean within three years or so.

A patent application has been filed and access to battery manufacturing facilities are being sought, either through forming a company or signing an agreement with an existing battery manufacturer. The resulting battery technology could spread to electric cars and domestic premises, for example, to hold solar power-generated electricity and power devices at night.